Behavioral predictors of improved speech output in minimally verbal children with autism

We investigated the relationship between eight theoretically motivated behavioral variables and a spoken-language-related outcome measure, after 25 sessions of treatment for speech production in 38 minimally verbal children with autism. After removing potential predictors that were uncorrelated with the outcome variable, two remained. We used both complete-case and multiple-imputation analyses to address missing predictor data and performed linear regressions to identify significant predictors of change in percent syllables approximately correct after treatment. Baseline phonetic inventory (the number of English phonemes repeated correctly) was the most robust predictor of improvement. In the group of 17 participants with complete data, ADOS score also significantly predicted the outcome. In contrast to some earlier studies, nonverbal IQ, baseline levels of expressive language, and younger age did not significantly predict improvement. The present results are not only consistent with previous studies showing that verbal imitation and autism severity significantly predict spoken language outcomes in preschool-aged minimally verbal children with autism, but also extend these findings to older minimally verbal children with autism. Autism Res 2018, 11: 1356-1365. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We wished to understand what baseline factors predicted whether minimally verbal children with autism would improve after treatment for spoken language. The outcome measure was change in percentage (%) syllables approximately correct on a set of 30 two-syllable words or phrases. Fifteen were both practiced in treatment and tested; the remainder were not practiced in treatment, but only tested, to assess how well children were able to generalize their new skills to an untrained set of words. Potential predictors tested were sex, age, expressive language, phonetic inventory (the number of English speech sounds repeated correctly), autism severity, and nonverbal IQ. Phonetic inventory and (for some children) autism severity predicted children's posttreatment improvement. Nonverbal IQ and expressive language ability did not predict improvement, nor did younger age, suggesting that some older children with autism may be candidates for speech therapy.